Various tire inflation systems for vehicles are well known to those skilled in the art. Wheel speed sensors to detect the wheel speed for various purposes, such the ABS system of the vehicle, are also well known, It is not generally well known, however, to combine a tire inflation system with a wheel speed sensor for a steering axle.
For example, U.S. Pat. No. 5,287,906 teaches an air delivery system for vehicles. The patent only generally states that the system can be used for the front axle of a vehicle. In the embodiment of the invention depicted and described in the patent, the system comprises a fixed axle having a fixed air line extending therethrough. The fixed air line is connected to a rotatable joint. The rotatable joint is located in the wheel hub of a wheel. The joint rotates with respect to the fixed air line and it transmits air from the line to a tee. The tee is located outside of the hub. Various air lines extend from the tee to the tires of the vehicle. The patent is silent regarding the use of wheel speed sensor.
U.S. Pat. No. 6,668,888 provides for a tire inflation system for a live spindle wheel assembly of a front drive/steering axle. The wheel assembly comprises a steering knuckle that supports a spindle assembly on a plurality of bearings. An inlet air passageway extends through the body portion of the steering knuckle at an angle to the axle. The inlet air passageway is in fluid communication with an air pressure chamber in the spindle assembly. A hub cap encloses the air pressure chamber within the spindle assembly except for a central aperture in the hub cap. The central aperture allows air to communicate from the chamber to the interior of a pneumatic tire. A drive shaft, located within the steering knuckle and the spindle assembly, is engaged with the spindle assembly for providing drive to the tire associated with the spindle assembly. The patent is silent regarding a wheel speed sensor.
U.S. Pat. No. 5,327,346 provides for a central tire inflation system for an all wheel drive vehicle. The system includes wheel speed sensors consisting of slotted discs attached to the wheel hubs of the vehicle. Data from the wheel speed sensors is sent to a computer that controls the tire inflation pressure of each tire. The inflation pressure can be raised or lowered if the wheel exceeds or drops below a pre-determined speed or if the wheel slips.
The prior art briefly discussed above suffer from various disadvantages. The most obvious disadvantage of U.S. Pat. Nos. 5,287,906 and 6,668,888 is that both lack a sensor. Additionally, the design described and depicted in U.S. Pat. No. No. 5,327,346 does not efficiently package both a tire inflation system and a sensor so that valuable area at the wheel end is wasted.
In light of the various disadvantages of the prior art discussed above, it would be advantageous to have a wheel end design that compactly incorporated a tire inflation system and a sensor, such as for the ABS system, for the steering axle of a vehicle.